Conventionally, drills have been provided of a type in which a leading end member to which a cutting insert is removably mounted is removably fixed to a drill body. Patent literature 1 discloses an example of the above described drills. There is also provided a drill in which the leading end member that can be removably mounted to the drill body is configured as a throw-away tip. FIG. 1 illustrates one example of such drills. In the drill illustrated in FIG. 1, the throw-away tip including a pair of cutting edges is removably mounted to the drill body with two screws.
An advantageous effect of the drill (hereinafter, referred to as a “head-exchange type drill”) of a type of exchanging such a leading end member is that, if the leading end member is exchanged to a leading end member in a different size, even when the body member is the same as that before the leading end member is exchanged, a hole having a different outer diameter can be processed. In other words, when one body member and a plurality of leading end members each corresponding to an outer diameter of the hole to be processed are prepared, holes in various types of sizes can be processed. Therefore, compared with a conventional drill in which a leading end portion and a body portion are integrated, such a head-exchange type drill can share the body member when a process is performed on the holes having the different diameters, thereby reducing a management cost. Further, when the leading end member of the drill of this type is for example worn out, or damaged, only the leading end member may be exchanged, thereby reducing a running cost and environmental load.